Lisa Yeo doesn't look like a junkie. The 47-year-old has shimmering blond hair and clear skin and wears a stylish tangerine shirt. It's Halloween, and her two dogs — a shih tzu and a dachshund — yap incessantly as trick-or-treaters come to the door of her house in Toronto.
Just eight years ago, she weighed 80 pounds and was missing her two front teeth.
Yeo's father gave her her first alcoholic drink at age 6, and she was drinking alone by age 11. As a teen, she developed a cocaine addiction, and in her early 20s, she set out on a path that would take her to heroin, crack, and prostitution.
On August 11, 2005, as cops walked her out of a hotel where they had found her shooting up, Yeo realized she was finally ready to change.
She went to rehab for a year, then a recovery house for another two years. But she still wasn't totally sober: For 18 years, she'd been receiving a court-ordered dose of the opiate substitute methadone. Now, she wanted off all drugs, once and for all.
As Yeo reduced her dose, her body started breaking down. Doctors told her that quitting the methadone was dangerous and advised her to just accept it as a fact of her life. To Yeo, the thought of staying on methadone was unbearable, and she began contemplating suicide.
Then she heard of a famous Canadian addiction specialist, Dr. Gabor Mate. Yeo set up a meeting.
"I told him this big, long story, and at the end of it, he said, 'Lisa, I think I can offer you a potential way out of this,' " Yeo remembers. "It was just like, 'Really?' "
First, Yeo spent a summer at a treatment clinic in Mexico, where she used other traditional plant medicines, iboga and ibogaine, to help wean her body off opiates. By October 2012, Yeo was ready for step two and boarded another plane to Mexico, this time for a weeklong ayahuasca retreat.
The night of her first ceremony, Yeo walked onto a round platform with a roof open to the jungle around it. Not long after she drank — "it tasted bitter, but it didn't taste as bad as some of the things I'd ingested in my life" — Yeo began to feel something prodding at her liver, damaged by hepatitis C.
"I felt what I thought of as a vine going into the area where I had the pain and circle, circle, circle," Yeo remembers. "Then there would be this release, and the pain would be gone."
The night of the second ceremony, Yeo's experience shifted: This time, she saw a slideshow of people who had shown her kindness, "babysitters to social workers to prison guards," Yeo remembers. "It was like flash cards, and at the very end was my mom."
Yeo has since done a second ayahuasca retreat with Mate and credits the vine with helping her discover who she is without substances.
"It has given me a go-to place of safety and a knowing of how to be gentle with myself when any tormenting thoughts creep in," Yeo says. "It just lifts the trauma; it lifts the pain."
Treatment for addiction disorders is one of the most promising areas of therapeutic ayahuasca use, in part because doctors still don't have many other good options.
"Someone walks in your office today, you're going to basically say the same thing your predecessor might have said 50 or 60 years ago, which is, 'Find a 12-step group, and if you're lucky and it's a good fit, maybe it will help,' " explains Grob. "Otherwise, we don't have a whole hell of a lot to offer."
The psycho-spiritual experiences that ayahuasca provides — "like a mystical-level state," Grob says — seem to offer an effect similar to that of certain faith-based aspects of 12-step groups: showing addicts that there is a power greater than themselves.
When Mate first heard of ayahuasca, he had recently published his book on addictions, In the Realm of Hungry Ghosts. People kept writing him, asking if he knew about "this weird plant," Mate remembers. Eventually, he decided to try it himself.
During his first retreat, Mate saw the connection to treating addiction right away.
"The ayahuasca experience just dissolved my defenses," he says. "I experienced a deep sense of love, tears of joy racing down my face."
Mate began organizing retreats of his own. He brought in shamans to lead the ceremonies and used his own training to help participants prepare for, process, and integrate what they experienced.
"It's not a question of 'Here's a drug that's going to fix you,' " Mate explains. "It's 'Here's a substance under the effect of which you'll be able to do a kind of self-exploration that otherwise might not be available to you or otherwise might take you years to get to.' "